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College of Food, Agricultural, and Environmental Sciences


Manure Covers Could Play Role in Mitigating Global Warming

December 9, 2009

COLUMBUS, Ohio – Technology to mitigate odor and air quality concerns on livestock farms can also be used for reducing greenhouse gas emissions, while providing potential income for farmers looking to trade carbon credits.

Manure storage covers, originally designed to control odors on dairy, swine and other livestock facilities, can also capture greenhouse gases such as methane, which is more harmful to the environment in terms of global warming effects than carbon dioxide. The collected methane can be traded for carbon credits at carbon trading markets, where the amount of gas measured is converted to its carbon equivalent. The amount the carbon is worth is then paid back to the farmer.

Lingying Zhao, an Ohio State University Extension agricultural engineer, said that farmers don't generally use manure covers because it's too costly. But the carbon credit programs and the loan support to use manure covers to mitigate climate change are now available to allow farmers to obtain manure covers at a fraction of the cost, or, if the farm is big enough, no cost at all.

"I see this as an opportunity for farmers to use a technology that not only would improve their on-farm situation, but also be profitable for them, as well as improve the environment," said Zhao, who also holds a research appointment with the Ohio Agricultural Research and Development Center.

Manure covers originally started out as natural materials, such as straw, that were placed over manure lagoons. But they weren't impermeable to gas emissions and degraded over time. Today's manure covers are made out of impermeable, synthetic materials that can last 10 or 15 years.

Zhao said that research is finding manure covers are serving more purposes than just controlling odors and reducing neighbor complaints. For one, they can capture harmful greenhouse gases, such as methane and nitrous oxide. Methane is estimated to be 21 times as intense a greenhouse gas as carbon dioxide, while nitrous oxide is 300 times more intense.

The greenhouses gases captured can then be put to environmentally friendly uses. Methane, for example, could be used as a biogas.

In addition, manure covers capture ammonia, increasing the value of manure used as a fertilizer.

"Without a manure cover, 36 percent to 90 percent of nitrogen is being lost to the atmosphere as ammonia," said Zhao.

Researchers realize the value of manure covers, but providing quantifiable information for farmers is still a work in progress. Zhao and her colleagues are leading a research project to determine just how much methane, nitrous oxide and ammonia manure covers can capture. They hope to develop a model that farmers can follow that will enable them to estimate methane production throughout certain times of the year for any given livestock operation.

In the meantime, Zhao and her colleagues have been holding manure cover workshops throughout Ohio to educate producers on manure covers and their benefits and connect farmers to resources for trying manure covers on their own farm.

One organization, Environmental Credit Corporation (, has been leading efforts to establish cost-effective, long-term projects with farmers that reduce greenhouse gases. One of those projects has been to provide manure covers at no cost to the farmer, and a prime example of their success has been with Miedema Dairy in Circleville, Ohio. The dairy farm runs the first lagoon cover program in the state, capturing methane, which is then measured and registered annually as carbon credits on the Chicago Climate Exchange.

There are also funding opportunities for manure covers offered through the Natural Resource Conservation Service as part of the Environmental Quality Incentives Program. Based on the conservation measures outlined in the 2008 Farm Bill, 60 percent of the funds to support EQIP will be used for livestock waste management.

Candace Pollock
Lingying Zhao